Hydrophilic deep eutectic solvents for bioactive compound extraction from Rubia tinctorum L

Area of Science:

• Phytochemistry
• Green Chemistry
• Analytical Chemistry

Background:

• Rubia tinctorum L. roots are rich in valuable anthraquinones and bioactive phytochemicals.
• Conventional solvent extraction methods can be environmentally impactful and lack selectivity.
• Deep eutectic solvents (DESs) offer a promising alternative for sustainable phytochemical extraction.

Purpose of the Study:

• To evaluate hydrophilic deep eutectic solvents (DESs) as green extractants for Rubia tinctorum L. roots.
• To compare the extraction efficiency of DESs with conventional solvents.
• To optimize extraction conditions and characterize the bioactive compounds obtained.

Main Methods:

• Nine hydrophilic DESs were synthesized and tested for extraction efficiency.
• Extraction performance was compared against acetonitrile, methanol, ethanol-water, and water.
• Response surface methodology was used for optimizing extraction parameters.
• Gas Chromatography-Mass Spectrometry (GC-MS) was employed for metabolite profiling.
• Antioxidant, antimicrobial, and phytochemical analyses were conducted.

Main Results:

• Choline chloride-based DESs, specifically choline chloride-lactic acid and choline chloride-malonic acid, exhibited superior extraction efficiency.
• These DESs selectively recovered gallic acid, caffeine, quercetin, alizarin, and purpurin.
• GC-MS analysis identified key metabolites such as alizarin, rubiadin, and purpurin.
• The extracts demonstrated significant antioxidant and antimicrobial activities.

Conclusions:

• Hydrophilic DESs are efficient, selective, and sustainable extractants for bioactive compounds from Rubia tinctorum.
• DESs present a viable green alternative to conventional solvents in phytochemical extraction.
• Optimized DES extraction yields potent extracts with valuable biological activities.